AEROLITES. 595 



tions in the aerolites of Blansko, Chantonnay and Alais. The 

 road happily pointed out by him beforehand has subsequently 

 been abundantly followed. 



" a. The first and more numerous class of meteoric stones, 

 those with metallic iron, contain this disseminated through 

 them, sometimes in larger masses, which occasionally form a 

 skeleton, 'and thus constitute the transition to those meteoric 

 masses of iron in which, as in the Siberian mass of Pallas, the 

 other materials disappear more considerably. On account of the 

 constant presence of olivin, they are rich in magnesia. The oli- 

 vin is that part of the meteoric stone which is decomposed when 

 it is treated with acids. Like the telluric, it is a silicate of mag- 

 nesia and protoxide of iron. That part which is not attacked 

 by acids is a mixture of feldspathic and augitic matter, whose 

 nature admits of being determined solely by calculation from 

 its total constituents, as labrador, hornblende, augite, or 

 oligoclas. 



" /3. The second much rarer class of meteoric stones have 

 been less examined. They contain partly magnetic iron ore, 

 olivin, and some feldspathic and augitic matter ; some of 

 them consist merely of the two last mentioned simple mine- 

 rals, and the feldspar tribe is then represented by anorthite. 30 

 CJirome iron ore (oxide of chromium and protoxide of iron) is 

 found in small quantity in all meteoric stones ; phosphoric 

 acid and titanic acid, which Rammelsberg discovered in the 

 very remarkable stone of Juvenas, perhaps indicate apatite and 

 titanite. 



" Of the simple sulstances hitherto detected in the meteoric 

 stones, there are 18 : 31 oxygen, sulphur, phosphorus, carbon, 



30 Shepard, in Sillimari's American Journal of Science 

 and Arts, ser. ii. vol. ii. 1846, p. 377; Rammelsberg, in 

 Poggend. Ann. Bel. Ixxiii. 1848, p. 377. 



31 Compare Cosmos, vol. i. p. 118. 



VOL. IV. X 



